The invention is in the field of radar simulating devices. In the prior art, radar simulators have been arranged to simulate the effects caused by ground reflections, targets, electronic countermeasures, etc., so that a trainee radar operator can observe the operating difficulties encountered by a radar operator in real life and thereby acquire experience. Heretofore, electrical connections between a radar and the simulator have been required in order for a simulator operator to be able to create the appearance of a target or of electronic countermeasures on the screen of a victim radar. This was inconvenient in a training situation and impossible when dealing with an unfriendly radar. This problem of the prior art has been overcome by the present invention which causes the effect of electronic countermeasures to appear on a victim radar scope, without requiring electrical connections between the victim radar and the invention.